Novel organo phosphorous antioxidantstabilizers and stabilized compositions containing same



United States Patent Oli ice 3,112,286 Patented Nov. 26, 1963 This invention relates to novel organo phosphorous compounds and more particularly pertains to novel of the foregoing type wherein x is a number of from i to 2 inclusive and y is a number of from 1 to 2 inclusive and the sum of the numerical value of x-t-y is always exactly 3.

The following reaction illustrates one method for pre paring the compositions embodied herein.

organic phosphite esters and to stabilized rubber compositions containing same.

The preparation of certain tri-aryl phosphite esters and their use as stabilizers is known. See, for instance, US. Patents Nos. 2,220,113; 2,220,845; 2,246,059; 2,419,354; 2,612,488; 2,732,365; 2,733,226 and 2,877,259.

An object of this invention is the provision of novel compounds having combined stabilizer-antioxidant activity. Another object is the provision of novel stabilized rubber latex. Still another object is the provision of novel rubber vulcanizates which are stabilized against attack by atmospheric oxygen.

That these and other objects have been accomplished by the present invention will become apparent to those skilled in the art upon a careful reading of the following description and examples.

The novel organic phosphite esters embodied herein have the structure f on 1 n i rt 2 3a i 3 (all; J x L y wherein R represents a bulky hydrocarbon group such as t-butyl, t-amyl, t-hexyl, cyclohexyl, t-pentyl, t-octyl, phenyl, and the like; R repraents hydrogen and R; R represents an alkyl group having from 6 to carbon atoms which is preferably in the meta or para position; x represents a number of from 1 to 3 inclusive; y represents a number of from 0 to 2 inclusive and the sum of the numerical value of x+y is always exactly 3. Most preferred are compounds of the foregoing formula wherein R is a tertiary alkyl group having from 4 to 8 carbon atoms; R is a member selected from the group consisting of hydrogen and R; R is an alkyl group having from 8 to 12 carbon atoms; x is a number of from 1 to 3 inclusive and y is a number of from O to 2 inclusive and the sum of the numerical value of x-i-y is always exactly 3. Even more highly preferred are compounds i ll. Q-rQ- Q C I! y wherein R, R R x and y have the aforementioned designations.

The novel organic phosphite esters embodied herein are useful as stabilizers which are most useful when incorporated into natural and synthetic diene rubber latex prior to coagulation and drying of the rubber. In addition to this these esters, unlike any of the known phosphite ester stabilizers, are very etlicient antioxidants in the subsequently vulcanized rubber.

The prior art phosphite esters such as triphenyl phosphite and the alkylated triaryl phosphites have been incorporated into rubber latex, and particularly GR-S or 5BR type of syntheic rubber latex prior to isolation of the rubber. The prime function of such stabilizers is the prevention of darkening deterioration and resinification of the polymer which is liable to occur when the coagulant is subjected to the elevated temperatures of the drying operation during manufacture. So great is the susceptibility of improperly stabilized unvulcanized SBR to oxidative deterioration at elevated temperatures that instances are known wherein the polymer has actually ignited during the drying operation. The prior art aryl phosphites and the novel phosphites embodied herein are very efiective in preventing this type of degradation.

Prior to the present invention it was necessary to use one type of a stabilizer in diene rubber latex to prevent the aforesaid darkening and resinification of the rubber after it is coagulated while it is being dried and then to employ a second different type of a compound as an antioxidant in the vulcanizate recipe employing the stabilized rubber. The aforementioned triaryl phosphites i and alkylated triphenyl phosphites are known to be useful as stabilizers for the raw rubber only, and to be of little or no value as antioxidants in rubber vulcanizates. The present invention is indeed unobvious and unexpected in that it has obviated the use of the heretofore necessary combination of separate stabilizer and separat antioxidant in the isolation and vulcanization of diene rubbers.

The novel combined stabilizer-antioxidants embodied herein have unusually good resistance to hydrolysis and is then emulsified in a 2 /2 sodium stearate solution with a Waring Blender. The resulting emulsion is then incorporated into the rubber latex as described above.

Mooney viscosities were determined for SBR 1511 samples stabilized with the specified amounts of stabilizer as described above. The Mooney viscosity value for the original and aged rubber appear in Table 1. The amounts Zinc oxide 5 Stearic acid 3 EPC carbon black 50 Altax (di-Z-benzolhiazyl disulfide) 1 To the above was then added on the mill Of stabilizer used in the samples appearing in Table 1 are f r 3 expressed as parts of stabilizer per 100 parts of rubber. Antloxldant 1 Table] STABILIZATION OF SBR 1511 RUBBER Mooney Viscosity (4 min.) Change Samples Aged at 105 C. in Air [or- Parts Stabilizer 0 i i 1 2 4 (i (lay day day days days days None (control) 44 +14 +26 +36 +48 t 1.25 POcgl m) 40 s 9 +1 +10 (311: $H OHaCCH:1 CIIFC-CII3 (E 3 1.25s.-. csnn @o-ro+@c +011 39 2 -5 -7 +4 +3 L CH3 2 (1H3 (1H3 CII -CCH3 CII3CGH;

(3H3 1.25.0. I-O C OH 37 13 3 +3 +8 $11 $11 CII3CCH3 CH:CCH:

3 1.25 HO (J- OH 37 1O +5 +13 (fIIa (11H; CH3.CCH3 CH5CCH3 $113 1.25 *CQII1Q+ 0P0 (3 7 0H 32 +2 +2 +2 +3 +3 CI]: 2

1.2s... (0911111- O *PO 32 0 +6 +12 CH3 (1H3 CH -C CH3 CII CCII OH: l 0.88 CnIIn O-P-O c+ +01 1 46 2 -7 +1 +3 +13 $11 CH3 CH3C-CH;| CII3-C-CH3 C s p l 0.88."... (C9II19- 0 P+oo- OIIJ 4e -1 -7 -c -1 +11 l L CIT: 1.4

*Nonyl phenol is the reaction product of phenol and propylene trimer. Values not determined.

EXAMPLE III A natural rubber-black masterbatch was prepared from the following recipe:

and the resulting stocks were cured at 140 C. for various lengths of time shown in Table 2. The cured samples were aged in air for 24 hours at 100 C. and the stressstrain properties were compared with the properties of Natural rubber 100 the unaged vulcanizate (Table 2).

Table 2 50' Cure Tensile psi. Samples Aired at 100 C. for Antitoxidant hour 24 hours 48 hours N one 4, 020 a, 100 70% retention) 1, s50 (42% retention).

(3H1 (1H3 c s-C-CII; CH3-CCII;

0 c- OH 4, 470 3, s50 (86% retention).. 3, 460 (77% retention).

| L C II; 3

P @CHn) 4, 320 3, 140 (73% retention) 1, 760 (41% retention).

(r: H: $113 CII;CC H: CH;CC H;

i HO 6 0H 4, 480 3,880 (87% retention) 3,300 (74% retention).

l C I'Ig i 0 H; C H; P i (1; 4, 300 3,870 (90% retention) 1 2,000 (67% retention).

CII;CCH; C11;- H;

(13H; 0 ({3 -OH L C II: 2

EXAMPLE IV Stabilizers of the type embodied herein as well as a known stabilizer were emulsified in water and the sta- 35 bility of the emulsions upon standing at 100 F. were determined. The emulsions contained solids and a standard amount of potassium oleate was used as the emulsifier. Stabilizers B and C below were in the form of liquids containing by weight of a parafiinic oil respectively. The emulsions each was made up to an initial pH of from 11.6 to 11.7. The emulsion broke when a clear oil layer appeared on top which could not be redispersed on stirring.

Stablizer ing 0.938 parts of stabilizer per parts of rubber and the results are given in Table 3.

i P 0,H,

i E -01r L Q I Q 2 In a manner similar to that given in Example II emulsion samples B and C above which had been aged for 15 days at 100 F. were used to stabilize SBR 1511 and Table 3 Mooney Viscosity (4 min.) Change Samples Aged at 0.111 Air for+ Stabilizer 0 1 2 4 0 day day day days days days Days to Break We claim:

1. A rubbery polymer of an open chain conjugated diene stabilized with from about 0.01 to about 5 percent Mooney viscosities were determined on rubber contain- 75 by weight based on said polymer of a compound having the structure wherein R is a radical selected from the group consisting of phenyl, cyclohexyl and tertiary alkyl groups containing from 4 to 8 carbon atoms; R is a member selected from the group consisting of hydrogen and R; R is an alkyl group having from 6 to 20 carbon atoms; x represents a number from 1 to 3 inclusive; y represents a number from to 2 inclusive and the numerical value of x-i-y is always 3.

2. An aqueous emulsion of 100 parts by weight of a rubbery polymer of isoprene stabilized with from about 0.25 to about 2 parts by weight of a compound having the structure (Eng 1 3 CIl'a-C Clls CH CI'lg-C-CIT] wherein x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the numerical value of x-l-y is exactly 3.

3. An aqueous emulsion of 100 parts by weight of a rubbery polymer of isoprene stabilized with from about 0.25 to about 2 parts by weight of a compound having the structure wherein x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the numerical value of x+y is exactly 3.

5. An aqueous emulsion of 100 parts by weight of a rubbery copolymer of butadiene-l,3 and styrene stabilized with from about 0.25 to about 2 parts by Weight of a compound having the structure wherein x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the numerical value of x+y is exactly 3.

6. A vulcanizate of a rubbery polymer of isoprene stabilized against attack by atmospheric oxygen contain- '10 ing from about 0.25 to about 2 parts "by weight per parts of polymer of a compound having the structure ou ou i i orn ment CTI C-Gm on; 1 no-m o--ro- -0um cm X wherein x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the numerical value of x+y is exactly 3.

7. A vulcanizate of a rubbery polymer of isoprene stabilized against attack by atmospheric oxygen containing from about 0.25 to about 2 parts by Weight per 100 parts of polymer of a compound having the structure (Tlla CH 1 c mugs-c m c In-c-cm wherein x is a number of from 1 to 3 inclusive; y is a number of from D to 2 inclusive and the numerical value of x+y is exactly 3.

9. A vulcanizate of a rubbery copolymer of butadiene- 1,3 and styrene stabilized against attack by atmospheric oxygen containing from about 0.25 to about 2 parts by weight per 100 parts of copolymer of a compound having the structure Cm out wherein x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the numerical value. of .r-i-y is exactly 3.

10. A compound having the structure R R1 i (7H3 1 r R21 n0 -0-1 L wherein R is a tertiary alkyl group having from 4 to 8 carbon atoms; R; is a member selected from the group consisting of hydrogen and R; R is an alkyl group having from 8 to 12 carbon atoms; x is a number of from 1 to 3 inclusive; y is a number of from 0 to 2 inclusive and the sum of the numerical value of x+y is always exactly 3.

11. A compound having the structure (131M (E113 cu e-c11 CIIr'C-OHI! l a uo- -c- -oP0-Giun) l J t wherein x is a number of from 1 to 2 inclusive and y is:

a number of from 1 to 2 inclusive and the numerical value of x-i-y is exactly 3.

11 12 12. A compound having the structure wherein x is a number from 1 t0 2 inclusive and y is a number from 1 t0 2 inclusive and the numerical value of T E x+y is exactly 3. CII;C-C]I; CH -G-OII; I

a l f \k 5 References Cited in the file of this patent Liloc1-O--P--(O illn) UNITED STATES PATENTS 0H3 2,058,394 Arvin Oct. 27, 1936 

2. AN AQUEOUS EMULSION OF 100 PARTS BY WEIGHT OF A RUBBERY POLYMER OF ISOPRENE STABILIZED WITH FROM ABOUT 0.25 TO ABOUT 2 PARTS BY WEIGHT OF A COMPOUND HAVING THE STRUCTURE 